Protecting your External USB thumb or hard disk is
an important step, specially if you save on them
vital or personal files, and you don't wish anyone
to have access to these files if the disk was lost
or stolen. In this articles I will be showing you to
to Encrypt an External USB disk with Mountain Lion
10.8

With previous versions of of OS X ,
we were used to encrypt the drive by using the Disk
Utility. However, with OS X Mountain Lion, the procedure
can be done directly on the mounted drive, either from
the Desktop or Finder.

From the Desktop or
Finder,
right click on the External Disk and click on
"Encrypt DiskName"...
, where DiskNameis the
name of the External drive, in my case, my USB disk
is named : External 8GB USB

You will be asked to type a
password and confirm it. Also you are required to
Type a password hint.

If you want any help in choosing a complex
password, then click on the Key icon
, and the
Password Assistant will launch.
Where you can specify the type and length of the
suggested password

Once the password is set by typing it or by
selecting a suggested password generated by the
PasswordAssistant and a password hint is typed as
well, Click on Encrypt Disk

Encrypting your disk
drive will start, You can verify this by right
clicking on the External disk and you will notice
the the Encrypt "DiskName"... is
now replaced with Encrypting "DiskName"...

The process of encrypting the disk takes quite a
long time depending on the disk size. Once the
External disk is encrypted, it will disappear from
your desktop and be mounted again. In this stage,
your disk is now encrypted, to verify this, eject
the disk and connect it again to your machine.

The next time you connect
your External disk into your machine, before the
device get mounted, you will be asked to enter the
encryption password so that you are granted access
to the external disk .

If you forgot your password, you can click on the
Show Hint button, so that you get a
hint for your password

Type your password and then click on the
Unlock button. Congratulations, now your
external disk is secured.

Note : Encrypting
your External Disk on OS X Mountain Lion will only make
it work and mounted on OS X Lion and OS X Mountain Lion.
Trying to connect the encrypted disk to OS X Snow
Leopard generated the below error message.

Summary

Encrypting your External Disk
drive or USB thumb is a must to do procedure if you have
files/photos on the disk drive and you don't wish anyone
to have access to the drive in case it was stolen or
lost. Its and easy process and a best practice process
to secure your data.